Deborah Siegel found herself so moved by graphic memoirist Phoebe Potts' infertility narrative, Good Eggs, she wrote her a letter.  And then she realized: we writers should do this more often.  It's like sending a karmic kiss. SHE WRITES ON FRIDAY PROMPT: Write a letter to an author you admire.   Here's mine.  Post yours in comments or on your SW blog (tag #shewritesonfriday).  We'll tweet the be…